21195993 has 16 divisors (see below), whose sum is σ = 34783616. Its totient is φ = 11180160.

The previous prime is 21195989. The next prime is 21195997. The reversal of 21195993 is 39959112.

It is an interprime number because it is at equal distance from previous prime (21195989) and next prime (21195997).

It is not a de Polignac number, because 21195993 - 2² = 21195989 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21195997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38548 + ... + 39093.

It is an arithmetic number, because the mean of its divisors is an integer number (2173976).

Almost surely, 2^21195993 is an apocalyptic number.

It is an amenable number.

21195993 is a deficient number, since it is larger than the sum of its proper divisors (13587623).

21195993 is a wasteful number, since it uses less digits than its factorization.

21195993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77664.

The product of its digits is 21870, while the sum is 39.

The square root of 21195993 is about 4603.9106203314. The cubic root of 21195993 is about 276.7480625333.

The spelling of 21195993 in words is "twenty-one million, one hundred ninety-five thousand, nine hundred ninety-three".